Method and apparatus for obtaining samples



All@ 7, 1945- J. o. LEWIS v METHOD AND APPARATUS FOR oTAImmGA SAMPLES Filed Feb. 28,' 1941.

2 Sheefs-Sheet l fer.

Patented Aug. 7, 1945` *UNITED STATI-:s` PATENT OFFICE METHOD AND APPARATUS FOR OBTAIN INGI SAMPLES James 0. Lewis, Houston, Tex., assignor 'of onehalf to Robert T. Wilson, Corpus Christi, Tex.

Application February 28, 1941, Serial No. 381,089

t 13 Claims.

This invention relates to a method and apparatus for obtainingwsamples, and more particularly a method and apparatus for obtaining representative samplesof .gas and its liqueable constituents from natural gas wells, especially from wells wherein the gas and its constituents have been subjected to conditions conducive to retrograde condensation. i

' It has been found that natural gas flowing from wells sometimes contains entrained hydrocarbon liquids and water, which gas and constituents existed in their strata of,` origin in yaporphase.

Through reduction in pressure and/or tempera# tures resulting from transfer ofthe -gas from the producing strata to the surface of the earth, part of the vapors become condensed because of the physical phenomena known as retrograde condensation occurring as a result of such transtwo-phase liquid and'vapor now, produced because of the noted retrograde condensation, are

Accurate sampling and/or metering of the shown operatively applied to a well, parts thereof being broken away to better illustrate its construction.

Fig. 2 is a vertical substantially central cross section through a regulated heater forming a `part of the apparatus for acting on lgas and its constituents to be sampled.

through a portion of the gas ow line showing diilicult for the reason that the liquids. are some- 'times produced irregularly and tend to follow the bottom o f horizontal flow pipes leading from the well. It has been attempted to overcome the diiculties in sampling and metering such twov phase flows by installing gasand oil separators at the well, together with other expensive equipment, and to ow the wells at different operating rates closely simulating actual production loperations. Such attempted expedients are expensive and time consuming. i

The principal objects of my invention are, therefore, to 'provide a convenient, economical and eilicient method and apparatus for obtaining representative samples of gases and their liqueable constituents' from natural gas wells.

Other objects of myinvention are to provide a methodand apparatus for correctly sampling well products in a relatively 'rapid Vand simple manner.l

Other objects of the invention are to provide improved steps in a method and improved elethe relation of the sampling device thereto.

vReferring more in detail to the drawings and to the method steps:

l designates the head of a gas well casing 2. that is suitably. extended tda producing stratum below the -surface of the earth 3, the casing being mounted in a suitable bore hole d and being provided with tubing leading from the well, The

tubing 5 preferably terminates in 'a tting t such as a T, the T having a suitable connection 'I with a pressure gauge 8 controlled by a valve 9.

A control valve I0 ispreferably mounted in a nipple or the like II leading from the lateral outlet I2 of the T I3, the valve I0 being connected by a suitable nipple or the like I3 with a regulated heater I4, the details of which are clearly shown in Figs.. 2 and 3.

The heater I4 .preferably consists of a section of pipe I5 enlarged in relation to the flow line I6 extending from the Adischarge or downstream end of the heater and to the nipples I I and I3 which form part of the ilow line well end of the heater. Opposite ends ofthe heater are provided with suitable reducers Il and I8, the outer extremities of which are provided 'with annular vflanges I9 and 20 that are secured to mating ilanges 2i and 22 Aon the nipple I3 and the flow line I6 respectively as by fastening devices 23 and 24. The heater I4 is also provided with spaced headers 25 and 2E` between which spaced tubes 21 extend for connecting the interiors of the v reducers 'I1 and' IB. 'Ihe space or spaces 4between the headers of the heater and its tubes is prefer-v ably lled with water 28 that may be applied to the interior of the heater, and particularly its reservoir surrounding the tubes, as by a fill opening .23 that is normally closed by a cap3ll.

An outlet 3l from the interior of the heater is controlled as by a valve and leads to a pressure gauge 32 for selectively measuring the pressure in the water space reservoir. A temperature and `pressure controloutlet 33 is also preferably provided for the heater. 'I'he outlet 33 leads to a relief valve 34 that may be regulated in ay suitable manner as by devices 35.

Mounted in the flow line I8 in spaced relation to the heater I4 and downstream relative thereto is a temperature Well 36 provided with a thermometer 31. v v

Also mounted in the flow line I6, in downstream relation to the temperature Well 36, is a metering device 38, preferably of orifice type and consisting of a, plate 39 arranged transversely of the flow line and provided with an orifice 40. The metering device 38 is also preferably provided with a recording element 4I for measuring pressures in the ow line adjacent-the metering device.

An outlet 42 from the flow line is preferably arranged downstream relative to the metering device 38 and on the well side of a flow line control valve 43, which outlet 42 is controlled by a valve 44 and leads through a connection 45 to a point adjacent and below the heater I4. The connection 45 is preferably capped, as at 46, and is provided with suitable heating elements 41 to provide for ignition of gases and constituents thereof in the outlet to heat the contents of the heater to desirable temperatures.

From the control valve 43-the ow line 1eads, as by sections 48 and 49, to suitable points of 'disposal for the products of the well passing through the line.

The ow line I6 is preferably provided with an opening 50 in the upper surface thereof arranged between the metering device and the outlet 42 from the flow line. A sampler tube 5I is mounted in the flow line through the openingv 50 and is preferably secured in position. 5 The sampler tube is provided with a longitudinally arranged slot 52, Figs. 4 to 6, of a length substantially equal to the inner diameter of the ilow line for allowing a cross-sectional sample of the contents of the flow line on the downstream side of the metering device to be received in the sampler tube. The sampler tube is preferably provided at its upper end with a control valve 53 that is connected by suitable devices 54 with a sampler receptacle or container 55 provided with control valves 56 and 51 at its opposite ends.

The method of the present invention may be conveniently carried out with an apparatus, vconstructed as above described, in the following manner:

Flow from the gas well through the tubing 5 is admitted to the flow line I6 in two phase condition by manipulation ofthe valves I and 43. Such ow of the gas, inclusive of its liqueable constituents, passes through the cylinder I by means of the tubes ltherein and is metered by the recording metering device 38. Some of the gas and its constituents may be admitted to the yheater line 45 by manipulation of the valve 44 which gas-is suitably ignited to heat the water or other suitable liquid in the cylinder.

Sufficient heat is applied to the cylinder to'revaporize all the condensates in the gas, i. e. to convert the two-phase flow to single phase. The heat aswell as the pressure produced in the cylinder is regulated by the control 34-35, the pressure being indicated by the gauge 32 and the temperature by the thermometer 31.'

It is then'desirable to regulate the flow of the gas through the lflow line by manipulation of the valve 43 to createidesirable back pressures between the valve 43 and the well, such pressures being recorded by the recorder of the metering device 38. The temperature of the gas in the flow line is also indicated by the thermometer in the temperature well 36.,

When the temperatures and the pressures of the single-phase flow have been regulated to the desired values, the sampler. container 55 is preferably first purged and then applied to its connections with the slotted sampler tube 5I. The sampler container 55 is preferably filled slowly under the control of the valves 53 and 56 in order that a. sample may be obtained over a consider- `able period of time, thus avoiding errors due to fluctuations in the rate of ow and' in the constituents of the flux.V Upon lfilling of the sampler container, the valves 53, 56 and 51 are closed and the sampler container is removed from the line, after which it may be taken to a laboratory for analysis of its contents.

The method above described may be repeated atsuitable intervals to determine'vari'ations in v -tion or otherwise.

' What I claim and desire to secure byfLetters Patentv is.: L

l. The method of obtaining truly representative samples of gas and its liqueflable constituents from a gas well so as to permit of accurate sampling and analysis consisting of converting iiuids flowing from said well in two-phase liquid and vapor flow to single-phase vapor flow, and collecting a sample of said single-phase flow for removal and analysis.

2. The method of obtaining representative samples of gas and its liqueable constituents from a gas well consisting of heating fluids owing from said well in two-phase liquid and vapor ow to effectv conversion to a single-phase vapor ilow, andcollecting a sample of said single-phase now for removal and analysis.

3. The method of obtaining representative samples of gas and its liqueable constituents from a gas well consisting of converting uids flowing from said well in two-phase liquid and vapor flow to single-phase vapor flow by applying regulated heat and pressure thereto, and collecting a sample of said single-phase flow for removal and analysis.

applying a back pressure to said ow, and col- .lecting'a sample of said single-phase flow for removal, and analysis thereof. l

5. The method of producing an accurate sample of a well uid for analysis consisting of withdrawing gas and liqueable constituents thereof from a well in two-phase ilow, diverting 6. The method of obtaining a sample of a welly fluid which is susceptible of accurate analysis consisting of producing gas and liquenable constituents thereof from a well in two-phase flow and the treatment thereof to admit of accurate metering and analysis which comprises, recording pressures incident to such production, controlling flow of the gas adjacent its point of available production, heating the gas and liquefiable constituents in said two-phase flow to convert the same toA single-phase vapor flow, recording pressures incident to heating said flow, regulating pressures incident to heating said flow, recording temperatures of said flow, metering said flow,

applying a back pressure on said flow, andcollecting and removing a sample of said singlephase flow substantially throughout the cross sectional area thereof for analysis thereof.

7. I n an apparatus for obtaining representative samples of gas and its liquefiable constituents from a gas Well, means for converting the output from said well in two-phase liquid and vapor flow to single-phase vapor flow, and means for collecting and removing a sample of said singlephase flow for analysis thereof.

8. In an apparatus for obtaining accurate representative samples of gas and its liquefiable constituents from a gas producing well for analysis to determine the composition thereof, means for converting fluids flowing from said well in two-phase liquid and vapor flow to single-phase vapor flow, means for metering the single-phase flow, and means for collecting and removing a sample of said single-phase ilow for removal and analysis thereof.

9. In an apparatus of the character described, the combination of means for producing gas inclusive of its liqueable constituents in twophase liquid and vapor flow, a ow line for said gas, means for applying regulated heat and presr sure to said gas to convert said two-phase flow to single-phase vapor flow, means for collecting and removing a sample of said single-phase flow area of said flow line so as to permit of an accurate analysis, and means for controlling now through said line.

10. In an apparatus of the character described, the combination of means for producing gas inclusive of its liquefiable constituents in two-phase liquid and vapor flow, a flow line for said gas, means forapplying regulated heat and pressure to said gas to convert said twophase flow to single-phase vapor ow,' a temperature well in said now line downstream relative to said heat and pressure applying means having a thermometer, means in said flow line for metering said single-phase flow, detachable in such single-phase, v

means for collecting a sample of said singlephase now from said flow line, and means for controlling flow through said line- 11. In an apparatus of the character de-v scribed, a sampling device for collecting a singlephase-flow gas sample from a horizontal flow line comprising means to convert any liquid phase in the flow to the gaseous phase, a tube mounted vertically in said line beyond said means and having a slot extending throughout the interior cross-sectional area of said line "r from top to bottom thereof, and means detachably connected with said tube for receiving and retaining the gas sample admitted to said tube `by said slot whereby an accurate analysis thereo-f may be obtained.

l2. In an apparatus of the character described, a flow line, means for selectively admitting gas in'two-phase vapor and liqueable constituent ovv to said flow line, a heater mounted in said lnow line consisting of a cylinder enlarged relative to the oW line having a liquid reservoir and having tubes allowing passage therethrough of said two-phase flow, means for diverting a portion of the flow from the flow line .to a point adjacent the heater for ignition to heat the (contents of the heater to convert the same to single-phase flow, means for creating a back pressure in the ilow line, a metering'- device connected to the flow line, a tube in the flow line arranged between the back pressure producing means and the metering device having a vertical slot extending substantially throughout the cross-sectional area of the now line, a sampler container connected with the tube, and means for selectively admitting and excluding samples of the flowfrom the tube and sampler container.

13. In an apparatus of the character described, a flow line, means for selectively admitting gas in two-phase vapor and liqueilable consitutent flow to said flow line, a `heater mounted in said flow line consisting of a cylinder enlarged relative to theflow line having a liquid reservoir and having tubes allowing passage therethrough of said two-phase now, means on the heater for recording pressures therein, means onthe heater for regulating temperatures and pressures therein, means for diverting a portion of the ow from the flow line to a point adjacentthe heater for ignition to heat the contents of the heater to convert the same to single-phase flow, a temperature well in the flow line, a metering device in the now line,

`means on the metering device to record pressures in the flow line adjacent the metering device, means for creating a back pressure in the flow line, a tube in the flow line larranged between the back pressure producing means and the metering device having a vertical slot extending substantially throughout the cross-sectional area of the flow line, a sampler container connected with the tube, and means for selectively admitting and excluding samples of the flow from the tube` and sampler container.

JAMES O. LEWIS. 

